Valve with resilient, bellows mounted valve seat

ABSTRACT

A rapid response poppet valve includes a valve body 10 with an internal cavity 16 in which a valve seat 100 is located. A poppet 70 is mounted for movement toward and away from the valve seat 100 and the valve seat 100 is resiliently biased toward the poppet 70 by a bellows 114 to resiliently mount the seat 100 and additionally seal the seat 100 to the valve body 10.

FIELD OF THE INVENTION

This invention relates to valves, and more particularly, to a poppetvalve construction provided with a resiliently mounted valve seat.

BACKGROUND OF THE INVENTION

Poppet valves have found substantial use in a large variety ofapplications. In a typical poppet valve, a poppet is reciprocated towardor away from a valve seat against which it may seal to halt the flow offluid or be spaced from the valve seat to permit the flow of fluid.While in most instances, the valve seat is rigidly mounted within a bodyhousing both the seat and the poppet, in some instances it may bedesirable to resiliently mount the valve seat or even provide aresilient valve seat. In a number of instances this is intended toenhance sealing, typically by allowing the sealing surface of the valveseat to adjust for radial, axial, and angular mismatches in thealignment of the sealing surface on the poppet and the sealing surfaceon the valve seats.

In other instances, resilient mounting of the valve seat may be toaccommodate the possible presence of solid material carried in a slurryor the like that happens to be interposed between the sealing surfaceson the poppet and on the valve seat when the latter is to be closedagainst the former.

Illustrative of constructions used for the foregoing are U.S. Pat. No.3,870,071 issued Mar. 11, 1975 to Graham et al and U.S. Pat. No.4,505,292 issued Mar. 19, 1985 to Osterode, respectively.

In addition, the resilient mounting of the valve seat provides somecushioning action as the valve is closed thereby reducing wear andpromoting longer life of the sealing components. This feature in valvesof this type is recognized in U.S. Pat. No. 2,840,336 issued June 24,1958 to Suthann.

SUMMARY OF THE INVENTION

It is the principal object of the invention to provide a new andimproved poppet valve of the type provided with a resiliently mountedvalve seat.

According to the invention there is provided a valve with a valvehousing including an inlet, and outlet and an interior cavity extendingbetween the inlet and the outlet. A valve seat is disposed within thehousing and in the cavity between the inlet and the outlet. A poppet isalso located within the cavity. Means are provided for mounting thepoppet for movement toward and away from the valve seat so that thepoppet may seat against or be spaced from the valve seat and a resilientbellows is employed to mount the valve seat within the cavity. Thebellows has a first end sealed to the valve seat, an opposed end sealedto the housing and a hollow interior defining a flow path from one ofthe inlet and the outlet to the valve seat.

As a consequence of the foregoing construction, the valve seat isresiliently mounted by the bellows to be shiftable within the cavity toachieve alignment with the poppet when engaged thereby. It will beappreciated that the use of a bellows achieves both a sealing and abiasing function in the inventive construction and provides goodcompensation for all forms of misalignment, namely radial misalignment,angular misalignment, and particularly, axial misalignment. Thus, thevalve is ideally suited for use in valves having high torque actuatorsbecause of the excellent cushioning in the axial direction provided bythe bellows, which minimizes wear.

In a preferred embodiment of the invention, the valve is adapted to haveits inlet connected to a source of higher pressure fluid and the bellowsis located on the inlet side of the seat with the poppet being locatedon the outlet side of the seat. As a result, the pressurized fluidacting against the interior of the bellows assists in biasing the seattoward the poppet to assure a good seal.

In a preferred embodiment of the invention, the end of the bellowsopposite that mounting the seat terminates in a rigid ring-like base.The base is provided with a radially outwardly opening groove and anO-ring seal is disposed in the groove to sealingly engage against thehousing.

Preferably, the cavity within the housing includes two steps ofprogressively reduced diameter and the bellows biases the valve seatagainst the second one of the steps. The ring-like base is held in placeagainst the first of the steps and the O-ring seal is disposed betweenthe steps in engagement with the cavity wall. Thus, the second stepserves as a stop for limiting movement of the valve seat toward thepoppet under the bias of the bellows and/or pressurized fluid at theinlet.

The invention contemplates the provision of a motor and drive housingsecured to the valve housing, which motor and drive housing is providedwith a bore opening toward the seat. A plunger is reciprocable withinthat bore and the poppet is mounted on the plunger. A rotary shaft and adrive motor therefore is located in the motor and drive housing and arotary to reciprocating motion converting mechanism interconnects theshaft and the plunger.

The invention further contemplates the provision of an additionalbellows sealed at its opposite ends respectively to the plunger and tothe cavity.

Other objects and advantages will become apparent from the followingspecification taken in connection with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a valve made according to the invention;and

FIG. 2 is an enlarged, fragmentary sectional view of the poppet, valveseat and bellows employed in the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

An exemplary embodiment of the invention is illustrated in the drawingsand with reference to FIG. 1 is seen to include a valve body 10 having abore 12 which serves as an inlet for connection to a source ofrelatively higher pressure fluid and an outlet port 14. Intermediate theinlet 12 and the outlet port 14 is a cavity 16 which extends to an openend 18 in the housing 10. The open end 18 can be closed by a cap 20which is removable from the body 10 but will normally be held in placeby a plurality of retaining screws 22 (only one of which is shown). Toseal the cavity 16, the cap 20 is provided with a peripheral O-ring seal24 to engage the periphery of the cavity 16 just inwardly of the end 18.

The cavity 16 will typically be cylindrical in configuration, having alarge diameter section 26 separated from an intermediate diametersection 28 by a first step 30 which in turn is separated from a smalldiameter section 32 by a second step 34. The small diameter section 32opens to an annular section 36 of the cavity 16 which in turn is influid communication with the outlet port 14.

Thus, a path of fluid flow through the valve in the direction of arrows40 and 42 and is established via the inlet 12, the cavity 16 and theparts thereof, and the outlet port 14.

To form the annular section 36 of the cavity 16, the upper ed 44 of thebody 10 is open and this in turn requires the provision of a supportingweb 46 in the resulting opening. A peripheral seal 48 is associated withthe supporting web 46 and the latter is held in place by beingsandwiched between the valve housing 10 and a motor and drive housing 50having a flange 52. The motor and drive housing 50 is secured to thevalve housing 10 by means of threaded fasteners 54 extending through theflange 52 and includes, at its upper end, a high speed stepper motor 56having a rotary output shaft 58 in engagement with a drive spring 60which is used to return the poppet to a known stop position in the eventof loss of electrical power to the motor 56. The output shaft 58 and thedrive spring 60 are coupled by any suitable means to a rotary shaft 62within the housing 50 and the shaft 62 journaled by thrust bearings,generally designated 64.

The shaft 62 extends into a cavity or bore 66 within the housing 50 inwhich a plunger 68 is reciprocally mounted. The plunger 68, at its lowerend, and within the cavity 16, mounts a frustoconical poppet 70. Aconventional ball nut assembly, generally designated 72, interconnectsthe plunger 68 and the rotary shaft 62 thereby serving as a rotary toreciprocating motion converting mechanism. Stated another way, dependentupon the direction of rotation of the output shaft 58 of the steppermotor 56, the plunger 68 will be reciprocated within the cavity 66 todrive the poppet 70 more deeply into the cavity 16 or to retract thepoppet 70 therefrom.

To prevent relative movement between the ball nut assembly 72 and theplunger 68, a retaining plate 80 held in place by threaded fasteners 82captivates the ball nut assembly 72 within a bore 84 in the plunger 68.

The poppet 70 includes a stem 86 which extends through an opening 88 inthe supporting web 46 to be threaded to the plunger as at 90. Theplunger 68 and/or the stem 86 may be keyed by means not shown to thehousing 50 or the supporting web 46 to prevent relative rotation withrespect thereto. Vent openings 92 may establish fluid communicationthrough the supporting web 46 so that fluid will not be compressed asthe plunger 68 moves downwardly within the bore 66, to avoid creatingresistance to such movement.

At the same time, to avoid leakage from the cavity 16 through the motorand drive housing 50, a bellows 94 is disposed within the bore 66. Theupper end 96 of the bellows 94 is in sealing engagement with theunderside of the plunger 68 while the opposite end 98 of the bellows 94is in sealing engagement with the supporting web 46 radially outward ofthe vent openings 92.

Located within the cavity 16 on the inlet side of the small diametersection 32 is a ring-like valve seat 100. As best seen in FIG. 2, thevalve seat 100 has an inner diameter 102 that is intermediate thediameters of the major and minor bases of the frustocone defining thefrustoconical valve member 70. As a consequence, a circular line ofsealing contact may exist at the location 104.

The valve seat 100, at its radially outer extremity, has an annular,radially outward directed flange 106 of reduced axial length from thatof the majority of the valve seat 100. The outer diameter is shown at108 and it will be appreciated from FIG. 2 that such outer diameter isless than diameter of the intermediate diameter section 28 of the cavity16. As a consequence, a small space 110 exists peripherally about thevalve seat 100.

The valve seat 100 is mounted on one end 112 of a resilient metallicbellows 114. The bellows 114 is of conventional construction, beinggenerally cylindrical and having a corrugated exterior designed by aplurality of aligned folds as is apparent from the drawings.

The opposite end 116 of the bellows terminates in a rigid ring-likemounting base 118. The mounting base 118 includes an annular flange 120which limits movement of the base 118 into the cavity 116 by engagementwith the first step 30. The ring-like mounting base 118 also includes anannular, radially outwardly opening groove 122 which receives an O-ringseal 124 for sealing engagement against the intermediate diametersection 28 of the cavity 16.

A snap ring 126 may be disposed in a groove 128 located within the largediameter section 26 to hold the ring-like base 118 in place.

It will be observed that by removal of the snap retainer 126 as well asthe cap 20, the valve seat 100, the bellows 114 and the ring-like base116 along with the O-ring seal 124 can be removed through the opening 18as a module.

As a result of the foregoing construction, the valve seat 100 is biasedby the bellows 114 against the step 34 which serves as a stop, limitingmovement of the valve seat 100 toward the valve 70. At the same time, itwill be appreciated that the valve seat 100 may move away from the step34 an appreciable distance against the bias of the bellows 114 whenengaged by the poppet 70 to compensate for a substantial degree of axialmisalignment. In this regard, it is preferable that the bellows 114 havea relatively low spring rate.

At the same time, it will be appreciated that by reason of theperipheral gap 110, the valve seat 100 may cant within the intermediatediameter section 28 of the cavity 16 or move from side to side therein;or combinations of both. Canting action of the valve seat 100compensates for angular misalignment between the poppet 70 and the valveseat 100 while side to side movement of the valve seat 100 compensatesfor radial misalignment of the poppet 70 and the valve seat 100.

It should be noted that even though the bellows 114 is chosen to have alow spring rate, positive sealing at the line of contact 104 between thevalves seat 100 and the poppet 70 occurs by reason of the location ofthe bellows 114 on the inlet side of the valve seat 100. In particular,the relatively higher pressure of the fluid at the inlet side will actagainst the interior of the bellows tending to expand the same thusproviding an additional biasing force for biasing the valve seat 100toward the poppet 70.

A valve made according to the invention will find many uses in thoseapplications where a resiliently mounted valve seat is desirable. Ahighly preferred use is in a refrigeration system where the valve isemployed to bypass a compressor with the inlet 12 connected to thedischarge side of the compressor and the outlet port 114 in fluidcommunication with the suction side of the compressor.

In many such systems, it is required that an adequate flow ofrefrigerant gas be maintained through the compressor, regardless of thecooling flow requirements of the system, to prevent compressor damagedue to surging, particularly when high speed centrifugal compressors areutilized. Through conventional control systems, the stepper motor 56 ofthe present valve may be operated to rapidly move the poppet 70 awayfrom the seat 100 to allow compressed refrigerant at the discharge sideof the compressor to back flow to the suction side to provide thenecessary refrigerant gas flow to prevent damage to the compressor. Thestepper valve 56 can also be utilized to move the poppet 70 to suitableintermediate, modulating positions so that the bypassing of refrigerantback to the suction side of the compressor provides only the necessaryquantity of refrigerant. However, in any such use, it will be recognizedthat a fast response is required which in turn will cause relativelylarge forces to be present when the poppet 70 contacts the valve seat100. However, these forces are taken up without causing accelerated wearby the unique mounting of the valve seat 100 by the bellows 114 all thewhile assuring positive sealing and compensation for misalignment causedeither by wear or by manufacturing tolerances.

Thus, a trouble free valve capable of providing rapid response andhaving long life characteristics and further being of modularconstruction is provided by the invention.

I claim:
 1. A valve comprising:a valve housing including an inlet, anoutlet and an interior cavity extending between said inlet and saidoutlet; a valve seat within said housing and in said cavity between saidinlet and said outlet; a poppet within said cavity; means mounting saidpoppet for movement toward and away from said valve seat so that saidpoppet may seat against or be spaced from said valve seat; a resilientbellows mounting said valve seat within said cavity, said bellows havinga first end sealed to said valve seat, an opposed end sealed to saidhousing and a hollow interior defining a flow path from one of saidinlet and said outlet to said valve seat, said opposed end terminatingin a ring-like base; a radially outwardly opening groove in said base;and an O-ring seal in said groove and sealingly engaging said housing;whereby said valve seat is resiliently mounted by said bellows to beshiftable within said cavity to achieve alignment with said poppet whenengaged thereby.
 2. The valve of claim 1 wherein said valve is adaptedto have said inlet connected to a source of higher pressure fluid andsaid bellows is located on the inlet side of said seat and said poppetis located on the outlet side of said seat.
 3. A valve comprising:avalve housing including an inlet, an outlet and an interior cavityextending between said inlet and said outlet; a valve seat within saidhousing and in said cavity between said inlet and said outlet; a poppetwithin said cavity; means mounting said poppet for movement toward andaway from said valve seat so that said poppet may seat against or bespaced from said valve seat; a resilient bellows mounting said valveseat within said cavity, said bellows having a first end sealed to saidvalve seat, an opposed end sealed to said housing and a hollow interiordefining a flow path from one of said inlet and said outlet to saidvalve seat; said poppet being frustoconical and said bellows biasingsaid seat toward said poppet; and stop means for limiting movement ofsaid seat toward said poppet; whereby said valve seat is resilientlymounted by said bellows to be shiftable within said cavity to achievealignment with said poppet when engaged thereby.
 4. The valve of claim 1further including a motor and drive housing secured to said valvehousing and having a bore opening toward said seat, a plunger reciprocalwithin said bore, said poppet being mounted on said plunger, a rotaryshaft and a drive motor therefor in said motor and drive housing, and arotary to reciprocating motion converting mechanism interconnecting saidshaft and said plunger.
 5. A valve comprising:a valve housing includingan inlet, an outlet and an interior cavity extending between said inletand said outlet; a valve seat within said housing an in said cavitybetween said inlet and said outlet; a poppet within said cavity; meansmounting said poppet for movement toward and away from said valve seatso that said poppet may seat against or be spaced from said valve seat;a resilient bellows mounting said valve seat within said cavity, saidbellows having a first end sealed to said valve seat, an opposed endsealed to said housing and a hollow interior defining a flow path fromone of said inlet and said outlet to said valve seat; a motor and drivehousing secured to said valve housing and having a bore opening towardsaid seat; a plunger reciprocal within said bore; said poppet beingmounted on said plunger; a rotary shaft and a drive motor therefore insaid motor and drive housing; a rotary to reciprocating motionconverting mechanism interconnecting said shaft and said plunger; and anadditional bellows sealed at its opposite ends respectively to saidplunger and to said cavity; whereby said valve seat is resilientlymounted by said bellows to be shiftable within said cavity to achievealignment with said poppet when engaged thereby.
 6. A valve comprising:avalve housing including an inlet, an outlet and an interior cavityextending between said inlet and said outlet, said cavity opening to theexterior of said housing and having first and second, progressivelyreduced diameter steps; a valve seat within said cavity between saidinlet and said outlet and axially movable to engage with said secondstep; a poppet within said cavity on the side of said second stepopposite said seat; means mounting said poppet for movement toward andaway from said valve seat so that said poppet may seat against or bespaced from said valve seat; and a resilient bellows mounting said valveseat within said cavity and axially biasing said seat toward said secondstep, said bellows having a first end sealed to said valve seat, anopposed end including a mounting ring engaging said first step andsealed to said housing between said first and second steps, and a hollowinterior defining a flow path from one of said inlet and said outlet tosaid valve seat; whereby said valve seat is resiliently mounted by saidbellows to be self-alignable with said poppet.
 7. The valve of claim 6including a cap removably and sealably mounted on said housing to closesaid cavity and removable to allow said seat, said bellows and said ringto be removed from said cavity as a module.
 8. A valve comprising:avalve housing including an inlet, an outlet and an interior cavityextending between said inlet and said outlet; a ring-like valve seatmovably received within said housing and in said cavity between saidinlet and said outlet; a frusto-conical poppet within said cavity on theoutlet side of said seat; means mounting said poppet for movement towardand away from said valve seat so that said poppet may seat against or bespaced from said valve seat; a stop within said cavity for limitingmovement of said valve seat toward said poppet; and a resilient bellowson the inlet side of said valve seat and mounting said valve seat withinsaid cavity, said bellows having a first end sealed to said valve seat,an opposed end sealed to said housing and a hollow interior defining aflow path from one of said inlet and said outlet to said valve seat,said bellows further biasing said valve seat toward said stop; wherebysaid valve seat is resiliently mounted by said bellows to be shiftablewithin said cavity to align with said poppet.